The present invention relates to an optical apparatus having a driving source for driving a lens in an optical axis direction, and particularly, to an optical apparatus which includes a vibration or electromagnetic type linear actuator for use as a driving source.
Some optical apparatuses include an electromagnetic type linear actuator or a vibration type linear actuator for use as a driving source for driving a lens (for example, see Japanese Patent Laid-Open No. 8 (1996)-179184, Japanese Patent Laid-Open No. 10(1998)-90584, and Japanese Patent Laid-Open No. 2004-046234).
In the optical apparatuses proposed in Japanese Patent Laid-Open No. 8(1996)-179184 and Japanese Patent Laid-Open No. 10(1998)-90584 having the vibration type linear actuator, each vibration type linear actuator is formed of a vibrator which produces vibration through an electromechanical energy conversion action and a contact member which is in press contact with the vibrator. For example, the vibrator is fixed to a lens holding member, the contact member is fixed to a stationary member of a lens barrel, and the vibrator is caused to produce driving vibration, thereby moving the lens holding member together with the vibrator.
The vibration type linear actuator is effective in reducing the size of an optical apparatus since it can generally be provided in a compact size as compared with the electromagnetic type linear actuator as disclosed in Japanese Patent Laid-Open No. 2004-046234.
However, the linear actuator disposed away from a light amount adjusting unit (aperture unit) on the outer side thereof as in the optical apparatus proposed in Japanese Patent Laid-Open No. 8(1996)-179184 leads to an increased size of the optical apparatus. Especially when such an arrangement is adopted in the optical apparatus which includes a lens to be driven by the linear actuator on each side of the light amount adjusting unit closer to an object and to an image plane, the optical apparatus is inevitably increased in size even when the compact vibration linear actuator is used.
In addition, the linear actuator is placed to interfere with the light amount adjusting unit in an optical axis direction, which makes it difficult to ensure large space for lens movement.